Field of the Invention.

This invention is directed to a method to produce a fibre product in powder or liquid form from plant material sugar cane, and particularly to a method which allows almost all the sugar to be removed from the product and possibly a subsequent treatment with high and/or low pH and mechanical degradation thereby providing a product with many versatile uses.

Background Art.

Plant fibres, when separated from the plant material and properly processed, provide a raw material which has a large range of uses.

One use for the fibre is as a dietary fibre as a fibre claim in foods.

The fibres have many other uses including fillers, bulking agents, water retention agents and enhancing the physical properties of various foods and beverages, a component of many types of compositions such as cosmetics, various types of medical products, various industrial products and compositions including a thickener for various industrial compositions (e.g. paint), an additive for a very large number of compositions including concrete and the like.

There are many known processes to enable plant fibres to be separated from the raw material.

If the fibre is used in an edible product (by which is meant any foodstuff or beverage), there is an advantage if the fibre is completely "neutral" by which is meant that the fibre is colourless, odourless and has no flavour. The advantage of such a "neutral" product is that the product can be easily incorporated into a foodstuff or beverage without altering the flavor of the foodstuff or beverage.

While some plant products can produce fibre powder which may have these desirable products, other plant products do not, and one form of the present invention is directed to a method by which a "neutral" product can be formed from a plant material which would otherwise produce "tainted" fibre powder (that is fibre powder that still has some undesirable components).

One plant material which has created great difficulties in easily providing a

"neutral" powder is sugarcane. Sugarcane is a good source of fibre, but, to date, it has been difficult, if not impossible, to provide a fibre product which is essentially free from residual sugar and/or a colour. It is found that residual sugar in the fibre product can create a flavour or taste to the powder which may make it more difficult to incorporate into various foodstuffs or other products. It is also found that residual sugar is prone to "caramelisation ", especially if the plant fibre powder is subjected to a heating step. This caramelisation can cause the powder to adopt an undesirable colour, taste or odour.

One form of the present invention is directed to a process by which a very usable supply of fibre product (typically dry fibre powder) can be obtained from sugarcane.

Sugarcane is a desirable plant material because the commercial part of the sugar cane is only essentially the sugarcane juice and the remainder of the plant is essentially discarded or used for low value products such as mulch, low-grade feedstuffs, or fuel for boilers.

It will be clearly understood that, if a prior art publication is referred to herein; this reference does not constitute an admission that the publication forms part of the common general knowledge in the art in Australia or in any other country.

Summary of the Invention.

The present invention is directed to a method for producing a fibre from a plant material, which may at least partially overcome at least one of the abovementioned disadvantages or provide the consumer with a useful or commercial choice.

In one form, the invention resides in a method to produce a fibre product a plant material comprising the steps of

a) harvesting the plant material;

b) size reduction of the plant material;

c) subjecting the plant material to an extraction step or steps to separate the sugar component from the fibrous plant material;

d) a pH modification step so as to be able to control the water retention properties of the fibre product;

e) drying the fibre product; and

f) milling to a specific size and/or shape.

In an alternative form, the invention resides in an integrated method of producing sugar or Juice and a fibre product from whole sugarcane comprising the steps of a) harvesting the sugarcane;

b) size reduction of the sugar cane;

c) subjecting the plant material to at least one extraction step to separate the sugar/juice component from the fibrous plant material;

d) downstream processing of the collected sugar/juice component;

e) pH modification of the fibrous plant material so as to be able to control the water retention properties of the fibre product;

f) drying the fibre product; and

g) milling to a specific size and/or shape.

As will be clear from the above, the method of the present invention can be used for producing a fibre product from any plant material but is particularly well suited to sugarcane and the invention is described with reference thereto.

In this specification, the term "whole cane" does not refer to the length of the sugar cane billets but rather to the use of all of each cane billet. Normally, the pith or rind (or both) of the cane are burnt for fuel for example, once the sugar syrup has been removed from them. According to the most preferred process, the process provided extracts the sugar syrup from the cane as one product and then further processes the pith and rind from which the sugar syrup has been removed to form a second, equally valuable, fibre product.

The extraction step is preferably a countercurrent extraction step however any diffusion or extraction method that allows the removal of Juice and sugar will suffice if it allows for sufficient extraction of sugar and subsequent treatment via pH modification, temperature and mechanical degradation.

It is found that this particular process can produce a fibre product (typically a dry powder) which is essentially free from residual sugar, and therefore is a product which is substantially colourless, flavourless and odourless and has controllable water retention properties and specific physical claims.

By having a low amount of residual sugar, the powder is not prone to caramelisation which can provide an "off-colour" to the powder and/or an undesirable taste or odour.

Thus, the powder can be used as an additive in various compositions where there may be further heating or treating steps to produce the ultimate end product (for instance a food product). The method is preferably used with sugarcane as the plant material and various varieties and cultivars of sugarcane may be used. These can include but is not limited to the following varieties Saccharum arundinaceum, Saccharum bengalense, Saccharum edule, Saccharum officinarum, Saccharum procerum, Saccharum ravennae, Saccharum robustum, Saccharum sinense, Saccharum spontaneum, and the like.

The sugarcane may be cleaned prior to use. The cleaning step may comprise an air blowing step to blow trash, dirt and debris off the billets, but may also comprise a cleaning step using water or something else.

The sugarcane typically comprises a relatively hard outer layer which is known as the "rind", and a softer internal portion which is known as the "pith".

After the cleaning process the cane is then subjected to a milling or shredding process to reduce the sugarcane to a particle size that is more susceptible to the diffusion process. In the first instance this is between 0.5-5mm but could vary from 5 μιη to whole stick cane.

The shredded cane is then subjected to an extraction step, which is preferably a countercurrent extraction step. The countercurrent extraction step preferably comprises a unit which has a rotating screw. It is preferred that the unit is at a slight angle upwardly away from the input end and that the shredded sugarcane material is added at the "lower end" of the unit and then is slowly worked by the rotating screw to the "upper end" of the unit and that an extraction liquid (typically water) is added at the upper end of the unit and gradually flows towards the lower end of the unit.

The counter current extraction step can extract a large amount of the sugar and preferably sufficient sugar such that the subsequently obtained fibre powder has the desirable properties of being colourless, odourless and flavourless. The effectiveness of extraction will typically be dependent upon the co-efficient of extraction which is typically dependent upon the extraction liquid chosen, time of extraction and whether recycle streams are used or not, as examples.

Typically, the unit has a length of between 3-20 m and preferably about

10 m or more. If desired, a number of units can be operatively coupled together such that the fibre material exiting from one unit can subsequently enter into the next unit for further removal of the sugar. It is preferred that the counter current extraction step is done under low shear conditions.

It is preferable that the counter current extraction step is conducted under controlled pH conditions which improve the extraction of sugar.

It is preferred that the counter current extraction step is conducted under a temperature which improves the permeability of the sugarcane cells thereby improving the ability of removing the sugar from the pith cell.

It is considered that a temperature of between 30-80° centigrade may be suitable with a preferred temperature range being between 40-70°.

An advantage with the heated particular counter current extraction step is that microbial and enzyme damage to the sugar cane material can be reduced. This type of damage may make it difficult to produce a "neutral" fibre powder.

Other types of extraction processes can be equally suitable and efficient for the process, as an alternative to the counter current extraction process.

During the diffusion process or immediately after, a pH treatment of the sugarcane may be used to degrade the fibre so as to give varying water retention properties. Normally, the mixture will be basic and an acid will be required. Citric acid is preferred as the acid. Citric acid also has a beneficial side effect of bleaching the material.

A mechanical degradation of the fibre may be utilized to assist in creating a desired physical property. Any mechanical degradation may be used in this step not limited to a decanter or press.

The "de-sugared" plant and degraded material can be conveniently termed "fibre product", although further steps may be required to obtain the desired end fibre product.

One further step includes a drying step. The drying step may be conducted using any convenient drying apparatus and it is preferred that the material moisture content is reduced to at least 20%, preferably less than 10% and most preferably about 4%.

The drying apparatus may comprise a flash dryer utilizing heated air with a classification step or impact mill drying using particle against particle in the drying process. If desired, the dried product can be milled or otherwise treated to provide the powder. It is considered that a powder form is quite convenient and suitable as a food additive or an additive to any other material including building material which would benefit from the fibre. Typically, the material is reduced to an average of 20 μηι, although it is not considered that the invention should be limited only to this material size.

In one form of the invention, the dried product is reduced in size to between 5-1000μιη utilising an air classification mill or air centrifuge mill. This alters the physical properties and use of the finished product depending of particle size and shape.

In an alternative form, the invention resides in a method to produce fibre product from plant material (and preferably sugarcane) comprising cutting the plant material into lengths, removing pith material from the cut plant material, subjecting the pith material to an extraction step to produce a reduced sugar fibre product, drying the fibre product and, if necessary, further treating the fibre product to provide a powder.

The extraction step is preferably a counter current extraction step.

It is found that this particular process can produce a fibre product (typically a dry powder) which is essentially free from residual sugar, and therefore is a product which is substantially colourless, flavourless and odourless.

By having a low amount of residual sugar, the powder is not prone to caramelisation which can provide an "off-colour" to the powder and/or an undesirable taste or odour.

Thus, the powder can be used as an additive in various compositions where there may be further heating or treating steps to produce the ultimate end product (for instance a food product).

The method is preferably used with sugarcane as the plant material and various varieties and cultivars of sugarcane may be used. These can include Saccharum arundinaceum, Saccharum bengalense, Saccharum edule, Saccharum officinarum, Saccharum procerum, Saccharum ravennae, Saccharum robustum, Saccharum sinense, Saccharum spontaneum, and the like.

The sugarcane can be initially cut into smaller lengths (sometimes called billets or bolts), and this can be done by the sugarcane harvester. This billets typically have a length of between 20-60 cm. Further cutting to a desirable length may be necessary.

The billets may be cleaned prior to use. The cleaning step may comprise an air blowing step to blow trash, dirt and debris off the billets, but may also comprise a cleaning step using water or something else.

The billets (that is the chopped stems of the sugarcane plants) typically comprise a relatively hard outer layer which is known as the "rind", and a softer internal portion which is known as the "pith". The pith portion typically comprises fibrous vascular bundles and pith material with the pith material containing the sugar juice. However, the term "pith" is often used to also include the fibrous vascular bundles and therefore generally includes all the soft material which is left after the harder outer rind layer has been removed. The fibre which is produced by the present invention may comprise fibre material in the fibrous vascular bundles and or the pith. The pith material can be removed taking advantage of the difference in the relatively hard outer rind layer and the relatively soft pith material. Thus, the billets may be initially cut or split longitudinally. There are various ways in which this can be done but one convenient way is to pass the billets (sometimes known as stalks) over a knife blade, which splits the billets into two halves or into at least the first part and a second part. Subsequently, the exposed in a pith material can be removed.

In one form of the invention, this can be achieved using a pair of rollers between which the billet passes with the rollers rotating at different speeds, and preferably with one roller rotating in the opposite direction.

The separation of the pith material from the rind will typically results in fracturing of a large percentage of the pith cells, and typically greater than 50% and preferably over 90% and even up to 98% of the pith cells. That is, it may be possible to fracture around 98% of the pith cells from the rind fibre. This usually does not release the juice substantially from the pith cells and the present invention includes further method steps to do so, as it is desirable to have substantially all the sugar removed from the pith fibre.

The separated pith material is then subjected to an extraction step, which is preferably a counter current extraction step. The counter current extraction step preferably comprises a unit which has a rotating screw. It is preferred that the unit is at a slight angle and that the separated pith material is added at the "lower end" of the unit and then is slowly worked by the rotating screw to the "upper end" of the unit and that an extraction liquid (typically water) is added at the upper end of the unit and gradually flows towards the lower end of the unit.

The counter current extraction step can extract a large amount of the sugar and preferably sufficient sugar such that the subsequently obtained fibre powder has the desirable properties of being colourless, odourless and flavourless.

Typically, the unit has a length of between 3-20 m and preferably about 10 m or more. If desired, a number of units can be operatively coupled together such that the fibre material exiting from one unit can subsequently enter into the next unit for further removal of the sugar.

It is preferred that the counter current extraction step is done under low shear conditions such that the relatively soft pith material is not subjected to undesirable shear.

It is preferred that the counter current extraction step is conducted under a temperature which improves the permeability of the pith cells thereby improving the ability of removing the sugar from the pith cell. It is desirable that the pith cells remain largely intact.

It is considered that a temperature of between 30-80° centigrade may be suitable with a preferred temperature range being between 50-70°.

An advantage with the heated particular counter current extraction step is that microbial and enzyme damage to the pith material can be reduced. This type of damage may make it difficult to produce a "neutral" fibre powder.

A double screw press may be used as an alternative to the CCE .

The "de-sugared" pith material can be conveniently termed "fibre product", although further steps may be required to obtain the desired end fibre product.

One further step includes a drying step. The drying step may be conducted using any convenient drying apparatus and it is preferred that the material moisture content is reduced to at least 20% and preferably less than 10% in most preferably about 8%.

The diying apparatus may comprise a fluid batch dryer comprising a vibrating hopper with a screen across the bottom with heated air being blown up through the product to dry the product. If desired, the dried product can be milled or otherwise treated to provide the powder. It is considered that a powder form is quite convenient and suitable as a food additive or an additive to any other material which would benefit from the fibre. Typically, the material is reduced to an average of 80 μ, although it is not considered that the invention should be limited only to this material size.

In one form of the invention, the dried product is reduced in size to about 200-250 μ using a grinder or granulator and thereafter is further reduced in size using a roller mill.

Another step may comprise a pressure heating step which can be conducted in an autoclave. The pressure may range from 100-400 psi. The temperature may range from between 100-250° and typically about 150°. Steam may be used to flow through the pith material. It is considered that a residence time of between 10 minutes- 12 minutes will be suitable. This will depend on the heat and pressure.

The pressure heating step can be seen as a "cooking process" which functions to allow soluble fibre to be obtained. If the pressure heating step is avoided, the resulting fibre may be substantially insoluble fibre only. Thus, manipulation of the "cooking process" can affect the soluble/insoluble fibre ratio of the final product.

Brief Description of the Drawings.

Various embodiments of the invention will be described with reference to the following drawings, in which:

Figure 1 is a schematic flowchart of a first part of a process flow according to a preferred embodiment of the present invention.

Figure 2 is a schematic flowchart of a second part of a process flow according to a preferred embodiment of the present invention.

Figure 3 illustrates a preferred drying apparatus to dry the material.

Figure 4 illustrates a preferred mill to grind the material into a powder.

Figure 5 illustrates a counter current extractor to remove sugar from the pith material prior to drying and grinding.

Detailed Description of the Preferred Embodiment. According to a preferred embodiment of the present invention, an integrated process for producing sugar and fibre powder from whole sugarcane is provided.

The integrated process of a preferred embodiment is illustrated in flowchart form in Figures 1 and 2. The cane will normally be transported from the harvester to the process. Normally, the harvester will already have cut the cane into billets. The process steps undertaken in the preferred process are as follows:

10. Weighbridge - in this step, the sugar cane harvested is weighed in order to calculate the payment to the farmer who grew the cane. The weighbridge step may also be used to determine the amount of solvent to be used in the sugar extraction step.

11. Washing - as the whole sugar cane will be used and will form a part of the fibre product, the sugar cane will normally be washed to remove trash, dirt and debris of the cane. Air or water or both will normally be used to clean the whole cane. 12. Shredder - The preferred shredder will typically be a two stage shredder. The first stage 11 will be the harvesting or billets the second stage will be the shredding of cane to a smaller size 12 this may be done in one or several steps to achieve the desired size for the extraction of Juice/sugar from the fibre.

13. Conveyor - the shredded sugar cane will then normally be conveyed to the countercurrent sugar extraction step 14. This will usually be performed using a conveyor 13.

14. Countercurrent sugar extraction (CCSE) - the CCSE step of the preferred embodiment is an inclined extraction unit with a helical screw conveyor to move the shredded sugar cane from the lower end to the upper end while extraction solvent, typically water, although the preferred embodiment also includes citric acid for contemporaneous pH adjustment, passes in the opposite direction from upper to lower end of the unit. The citric acid has a dual effect when used in this manner of bleaching the solids in the shredded sugar cane. Therefore, juice 33 normally exits the extraction unit at the lower end and fibre 34 at the upper end, although there is likely to be some of the solids in the juice exiting the unit and some juice in the solids.

15. Screen Press - the juice exiting the lower end of the extractor 14 may then pass through a screen press 15. The screen press 15 which presses the juice from the extractor 14 will also typically separate the fibre 34 from the raw juice. The fibre can be combined with the fibre from the top end of the CCSE unit.

Centrifuge - the juice exiting the screen press 15 is then preferably centrifuged/decantered 16 in order to separate the juice from any wax or further fibre which may present in the juice.

Cross flow filters - the centrifuged juice will then be forwarded to a crossflow filter 17.

Reverse osmosis - the filtered juice will typically pass through one or more reverse osmosis filters 18 in order to remove any water which might remain in the juice from the juice. Typically, the water 35 removed in the reverse osmosis filters 18 may then be recycled to the top end or solvent inlet of the countercurrent extraction unit 14. The juice exiting the reverse osmosis filters 18 can then be further processed to produce sugar or used in its existing form.

pH Vat - the fibre exiting the top of the counter current extraction step normally passes through a pH vat 19 in order to adjust the pH of the fibre. Typically, the pH vat also contains citric acid which continues the bleaching effect on the fibre. Press - the pH adjusted fibre exiting the pH vat 19 may then pass through a screen press 20 in order to mechanically degrade the fibre further. Any juice or water which is produced by this step may be either wasted or recycled to the upper end of the counter current extractor 14.

Decanter - either alternatively or in combination with the press, the pH adjusted fibre exiting the pH vat 19 may pass through a decanter 21 in order to separate the fibre from any wastewater or juice which again may be either wasted or recycled to the upper end of the counter current extractor 14.

This Vat and Decanter step may be performed without the CCSE but after the shredder if it is deemed to be more efficient

Conveyor - the fibre exiting the press 20 and/or decanter 21 will typically then be conveyed to a drying step 23.

Dryer - the dryers of the preferred embodiment are preferably flash dryers. These dryers 23 will typically dry the fibre product to less than 10% by weight of water content. 25. Cooling - the dried fibre product exiting the dryers 23 will normally undergo a cooling step prior to milling. In order to maintain the feed into the mill 25, a surge hopper 36 may be provided.

26. Milling - the milling step will typically reduce the size of the fibre product to between 5 μ and 1000 μ. However, the preferred size is an average of 20 μ. In order to ensure the preferred size, an air classifier 37 is preferably used in combination with the mill 25. This ensures that only milled fibre of a particular size passes the mill 25 and any milled fibre which is over size is returned for further milling.

27. Bag Filter - the fibre product exiting the mill 25 at the target size or range will then typically pass through a bag filter 26.

28. Particle Remover - the filtered fibre product will then typically pass through a foreign particle remover 27 before proceeding to a bagging step 38 where the product is packaged into bags for transport.

29. Metal detector - prior to dispatch, the bank product passes through a metal detector in order to ensure that no metal is contained in the product.

30. Palletisation - once the final checks have been done, the bank product is then placed onto or into pallets for storage prior to transport. Referring to Figure 1 : sugarcane is passed into a shredding or milling apparatus to reduce its particle size to a preferred size of 0.5-5mm with a uniform shape and size to aid in the diffusion process, the resultant material would retain its juice and fibre components and be free of long strands of sugarcane

The shredded/milled material then passes into a counter current extractor an example of which is illustrated in figure 5: The apparatus has a helical rotating screw which occupies the diameter of the trough and which can be 10 m or more in length. The apparatus has a gradual up flow of feedstock and this is achieved by inclining the entire apparatus at an angle of about 6°. The sugarcane material from the first step is introduced at the lower end of the apparatus and is slowly worked towards the upper end by virtue of the helical screw.

A sugar removing solvent (water) is introduced at the upper end and works its way down through the pith and rind material (solids) to the lower end. The temperature profile of the solids fraction within the trough is controlled by the temperature of the jackets and by recycling some of the juice stream through an external heat exchanger and back into the incoming pith material.

During the upward movement of the solids, the rotation mechanism is reversed periodically to ensure intimate contact between the counter flowing liquid 5 and the pith material. The slow rotation of the single screw ensures minimal sheer in the process.

The temperature profile in the apparatus denatures the cell wall of the plant material which becomes very permeable and therefore enables sugar to be removed from the material but with the structural integrity of the cells remaining 10 largely intact (that is the plant material cells do not disintegrate).

The elevated temperature profile reduces microbiological and enzyme damage to the solids.

During this stage the pH level of the extract may be varied to give differing physical properties of the finished product.

15 In an embodiment of the invention based on trials with a small counter current extraction apparatus, the following operating conditions were used for a high pH extraction run:

Operating Conditions

Date: 18th November 2008

Product: Sugar Cane

Trial Number: 3

Start Time: 8:51am

Time

Parameters Units 9.40am 10.10am 10.40am 11.10am

Extract pH 5.1 4.6 4.3 4.4

Ratio - solids: liquid 1:3 1:3 1:3 1:3

Ext. solvent flow rate mls/min. 200 200 200 200

Solids feed rate g/mm ^' . 66.6 66.6 66.6 66.6

Recycle flow rate pump n/a n/a n/a n a

Brix (solids in) °brix

Brix (extracted Juice) °brix 7 10.8 10.8 5

Brix (Solids Discharge) °brix 0 0 0 0

Recycle Temp. °c n/a n/a n/a n/a

Extraction solvent temp. °c 45 45 45 45

Trough Temp. °c 25.5 23.4 22.5 22.5 final product temp °c

Hot water temp. °c 55 54 52 52 forward time Seconds 17 17 17 17 reverse time Seconds 12 12 12 12 screw speed 6 6 6 6

Extraction Solvent pH 9.7 9.7 9.5 9.5 extraction solvent - volume

used Its 32.1

Extracted Juice - final volume Its 21.395

Solids In kgs 8

Solids Out kgs 15.895

Residence time hour 1

Discharge Moisture % 89.57

[Notes

started with a 61t pool @ 45 c

200grams/ 3 minutes - 4 kgs / hour

Started solvent @ 912am 600mm from screen

stopped feed @ 10.51am

stopped solvent @ 11.18am

Extraction solvent was adjusted to 9.6 pH using caustic

Date: 19th November 2008

Client: KFSU Pty Ltd

Product: Sugar Cane Bagasse

Trial Number: 6

Start Time: 11:42am

Notes

Used Citric acid to adjust pH of solvent

Notes: Started with a pool of 6 Its @ 45C

Feed rate of 200grams / 3 minutes = 4kgs/hour turned solvent on at 12.00pm 400mm from screen

Product absorbing a lot of solvent pool level getting low, stopped feed at 1.42pm In an embodiment of the invention based on trials with a small counter current extraction apparatus, the following operating conditions were used for a low pH extraction run:

Figure 3: shows the flash dryer into which the de-sugared product is placed and dried to specifications in this case with a T500G flash dryer.

The dried and substantially sugar free sugarcane material is transferred to a milling apparatus to reduce the particle size into powder form.

Figure 4: illustrates a milling apparatus that may be used in the embodiment of the present invention. The mill in this case is a Bauermeister gap mill with associated air classifier (BM ACL). The milling apparatus mills the material to a powder of an average 20 μηι size which is then bagged prior to shipping.

The method according to the invention enables the fibrous material from sugar cane to be value added into a powder containing some soluble but mostly insoluble fibre material and where the powder is essentially "neutral" and therefore suitable for an enormous range of uses.

Throughout the specification and the claims (if present), unless the context requires otherwise, the term "comprise", or variations such as "comprises" or "comprising", will be understood to apply the inclusion of the stated integer or group of integers but not the exclusion of any other integer or group of integers.

Throughout the specification and claims (if present), unless the context requires otherwise, the term "substantially" or "about" will be understood to not be limited to the value for the range qualified by the terms.